1. Field of the Invention
The present invention relates to a method of detecting a shock and a shock sensor based on the characteristics of a field-excited phase transition material or piezoelectric/electrostrictive material for bringing about a phase transition from an antiferroelectric phase to a ferroelectric phase in response to the application of an electric field thereto.
2. Description of the Prior Art:
When a piezoelectric material is subjected to an external force, it generates a voltage proportional to the magnitude of the applied external force. A shock sensor which operates based on such piezoelectric characteristics is known from Japanese laid-open patent publication No. 1-221674, for example.
The piezoelectric device of a conventional shock sensor generates an output voltage proportional to the magnitude of an external force applied thereto even when no electric energy is supplied to the piezoelectric device. In order to detect a shock greater than a predetermined level, however, it is necessary to combine a voltage monitoring circuit with the shock sensor for generating an output shock signal when the voltage monitoring circuit detects an output voltage from the shock sensor which is higher than a predetermined reference voltage. The voltage monitoring circuit needs to be supplied with electric energy from an external source to enable the shock sensor to detect an applied shock greater than a predetermined level.